The Unlicensed Mobile Access (UMA) and General Access Network (GAN) specifications define keep-alive mechanisms that perform different functions. Generally, the keep-alive mechanism informs the network when a mobile station (MS) has disconnected. This occurs when the network stops receiving periodic keep-alive messages from the MS. After the MS disconnects, the network can eventually release network resources previously linked to the MS and optimise the use of resources in GAN controller (GANC). In addition, when no other message is flowing on the link, the continual sending of periodic keep-alive messages by the MS permits maintaining Transmission Control Protocol (TCP) socket flow.
In paragraph 6.5 of the GAN Specification, when the mobile station (MS) receives a Generic Access Resource Control (GA-RC) Register Accept message, the MS initiates the GA-RC keep-alive mechanism by starting a TU3906 timer using a TU3906 time value received in the message. In one known process, when the TU3906 timer expires in the MS, the MS sends the GA-RC keep-alive message to the GANC and re-starts the TU3906 timer. A consequence of the GAN specification is that upon receipt of the GA-RC Register Accept message, the MS sends a GA-RC Keep-Alive message upon every expiry of the TU3906 timer, without regard for other procedures that may be performed by the MS. For example, if the TU3906 timer expires during a Generic Access Circuit Switched Resources (GA-CSR) signalling procedure, the MS sends a keep-alive during signalling, which is not necessary efficient.
U.S. Publication No. 2008/0025258A1 entitled “UMA/GAN Keep-Alive Mechanism In Wireless Communication Networks” discloses a wireless communication user terminal that re-sets the TU 3906 timer upon transmission of a message thereby preventing expiration of the timer and the unnecessary transmission of keep-alive messages. For example, the TU 3906 timer may be re-set when the user terminal sends a Generic Access Circuit Switched Resource (GA-CSR) message or a Generic Access Packet Switched Resource (GA-PSR) message or some other message on the TCP socket.
The various aspects, features and advantages of the disclosure will become more fully apparent to those having ordinary skill in the art upon careful consideration of the following Detailed Description and the accompanying drawings described below. The drawings may have been simplified for clarity and are not necessarily drawn to scale.